Supersonic compressor with axially transverse discharge



Sept. 20, 1960 E. A. STALKER 2,953,295

SUPERSONIC COMPRESSOR WITH AXIAL-LY TRANSVERSE DISCHARGE Filed Oct. 22,1954 I l 72 2 62 2 L O 2 JNVENTOR.

United States PatentO SUPERSONIC COMPRESSOR wrrn AXIALLY TRANSVERSEDISCHARGE Edward A. Stalker, 406 N. Farragut St., Bay City, Mich. FiledOct. 22, 1954, Ser. No. 463,975

Claim 2 0) This invention relates to compressors for elastic fluids. Anobject ofthis invention is to provide acompressor whose rotating bladesoperate at supersonic velocity relative to the fluid or to the}compressor case,

' Other objects will appear from the description, drawings and claims.

application. discloses a, rotor similar in some respects toithat in myapplication Serial No. 433,890 filed June 2, 1954, now Patent No.2,839,239 entitled Supersonic Axial Flow Compressors.

The aboveobjeets are accomplished by the means illustrated in theaccompanying drawings in which Fig. 1 is a fragmenta y axial sectionthrough a compressor according to this invention;

Fig. 2. is a section of the blading on line 2 2 in Fig. 1; and

Fig. 3 is a rear axial view of the compressor of Fig. 1.

Referring now to. the drawings, the compressor is indicated generally asin Fig. 1. It comprises th ase and the. rotor 1.4. The rotor is mountedby shaft 22 in thebearings 26. The inlet guidev vanes are 18.

The rotor 14 includes. the hub 32 upon which are carried, the rotor mainblades 1 6 (Figs. 1 and 3) peripha erally; spaced thereab'out with therotor flow passages 40 between them extending from the front to the rearsides of the rotor. Between each pair of main blades there is anauxiliary element 42 whose function will be discussed subsequently.

The case and hub define an annular channel 70 having the annular inlet'12. The rotor blades span this channelv and preferably fitclosely tothe case at their tips along substantially their whole chord length.

When the rotors are rotated by means of one of the shafts, a flow offluid, air for instance, is induced throughv the channel and at highrates of rotation the fluid velocity relative tothe rotor blades becomessupersonic.

The rotor blades have theirleading edges LE. inclined rearward ordownstream at their tips. Thus the leading edges are inclined to therelative flow vector80 as shown in Fig. 1. This line passes through theleading edge. The magnitude of this vector 80 and the inclination of theleading edge are such that the normal component 82 is less than thespeed of sound in the local fluid, that is fluid just ahead of theleading edge.

Since the component 82 is subsonic the flow will enter the rotorpassages 40 without the formation of shock waves but will be supersonicin the passages.

The rotor passages preferably decrease in cross sectional area rearwardtherealong up to a throat 90. The auxiliary element 42 ineach passagehas its leading edge preferably adjacent to or somewhat downstream fromthe throat. Theleading edge L.E. of the auxiliary element is preferablyless inclined or normal to the flow so as to precipitate-a shock wave 91which will stand in a position a short distance ahead of the edge. Aftof the shock wave the fluid velocity will be subsonic.

The auxiliary elements 42 define auxiliary flow passages 92 betweenthem, each increasing in cross sectional area ice rearward therealongwith each exit thereof greater in cross sectional area than each illwetof passages 40. The main blades preferably extend rearward substantiallyparallel to the auxiliary elements 4 2 dividing the auxiliary passagesinto substantially equal portions 93 and 94 extending substantially inthe general direction of the main blades.

Although it is preferred to precipitate the shock wave by having theleading edge of the element less inclined than the blade leading edge,the shock wave may also be precipitated by diverting the supersonic flowperipherally. This can be accomplished by making the leading edge of theauxiliary element relatively blunt or wellcurved or b g ving the elementa substantial thickness. in the peripheral direction of the rotor.

The flow entering the rotor passages decreases in speed because of therearward decreasing cross sectional areas. The flow remains supersonicbut the velocity decreases toward the value of Mach number 1 at thethroat. The minimum loss will occur if the shock wave occurs with thelowest Mach number. Accordingly the auxiliary element 42 preferably. ofblade shape has its leading edge near the throat. It will precipitateand stabilize a shock wave near its leading edge.

The rotor blades preferably have relatively. sharp leading edges asshown in Fig. 2 and preferably the inlet guide vanes direct the flowagainst the direction of rotation of. the rotor. v The shock waveconverts the high supersonic velocity. of the relative flow through therotor passages to static pressure. The fluid at high static pressureflows into the collector space and out the discharge duct 102,

The passages 40 increasein cross sectional area rearward (downstream)from the location of the leading edge of the auxiliary blades 42 toaccommodate the same mass rate of flow of fluid which is moving moreslowlyv just aft of the shock wave. The fluid velocityis prefcra blyfurther reduced well aft of the shock wave by the increasingcrosssectional areas of the passages. Then.

at the exit the fluid has a large peripheral velocity. com.- ponentadapting the fluid to flow out the duct 102, that 1s in-a directiontransverse to the axis of rotation.

It is preferred, to have no fluid turning stator vanes in the circularcross sections of the case immediately ad.- jacent the downstream sideof the rotor. The flow leaves the rotor with chiefly a peripheral.component of velocityand; so is being directed chiefly transversely ofthe axis toward the exit duct without the aid of vanes.

It will now be clear that. I have provided a novel com; pressor-capableof high pressure ratios with high-efficiency.

While I. have illustrated specific forms of the invention, it is to beunderstood that variationsmay be made therein and that I intend toclaimmyv invention broadly as indicated by the appended claims.

I claim:

1. In combination in any axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprisinga, hub and a plurality of peripherally spaced main blades carriedthereon, said blades and said hub and said case in cooperation definingrotor flow passages for conduction of said fl-uid therein at supersonicvelocity relative to said rotor, each said passage having a. frontportion of decreasing cross sec: tional area rearward therealongsucceeded byv a portion of rearward increasing cross sectional areadefining a throat of each said passage between the front and rear sidesof said rotor for reducing said supersonic velocity. to a lower valuethereof at said throat, each said blade having its leading edgesubstantially inclinedrelative to a line through said edge normal to thedirection of said flow adjacent to said edge providing relative velocitycom:- ponents of. said fluid normal to said edge of subsonic;

values relative thereto, an auxiliary element in each said passageextending radially thereacross over substantially the whole radialextent thereof and subject to said supersonic relative fluid velocitytherein with the leading edge of said element positioned adjacent tosaid throat and directed substantially more normal to said flow in saidpassage than the leading edges of said blades for precipitating a shockwave at the leading edge of each said element during operation of saidcompressor, and a shaft secured to said hub for rotating said rotor insaid case at a blade tip speed relative to adjacent said fluid greaterthan the velocity of sound in said fluid upstream adjacent said bladesduring operation of said compressor, said case having circular crosssections thereof downstream adjacent said rotor and free of fluidturning stator vanes for receiving fluid from said rotor across saidsections with chiefly a peripheral component of velocity said casehaving a discharge duct directed transversely to said axis for directingfluid from said case transversely to said axis.

2. In combination in an axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprising ahub and a plurality of peripherally spaced main blades carried thereon,said blades and said hub and said case in cooperation defining rotorflow passages for conduction of said fluid therein at supersonicvelocity relative to said rotor, each said passage having a frontportion of decreasing cross sectional area rearward therealong succeededby a portion of rearward increasing cross sectional area defining athroat of each said passage between the front and rear sides of saidrotor for reducing said supersonic velocity to a lower value thereof atsaid throat, each said blade blade having its leading edge substantiallyinclined relative to a line through said edge normal to the direction ofsaid flow adjacent to said edge providing relative velocity componentsof said flow normal to said edge of subsonic values relative thereto, anauxiliary element in each said passage extending radially thereacrossover substantially the whole radial extent thereof and subject to saidsupersonic relative fluid velocity therein with the leading edge of saidelement positioned downstream from said throat and directedsubstantially more normal to said flow in said passage than the leadingedges of said main blades precipitating a shock wave at the leading edgeof each said element during operation of said compressor, and a shaftsecured to said hub for rotating said rotor in said case each at a bladetip speed for each said blade relative to adjacent said fluid greaterthan the velocity of sound in said fluid upstream adjacent said bladesduring operation of said compressor, said case having circular crosssections thereof downstream adjacent said rotor free of fluid turningstator vanes for receiving fluid across said sections from said rotorwith chiefly a peripheral component of velocity, said case having adischarge duct directed transversely to said axis for directing fluidfrom said case transversely to said axis. 7

3. In combination in an axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprising ahub and a plurality of peripherally spaced main blades carried thereon,said blades and said hub and said case in cooperation defining rotorflow passages for conduction of said fluid therein at supersonicvelocity relative to said rotor, each said passage having a frontportion of decreasing cross sectional area rearward therealong succeededby a portion of rearward increasing cross sectional area defining athroat of each said passage between the front and rear sides of saidrotor for reducing said supersonic velocity to a lower value thereof atsaid throat, each said blade blade having its leading edge substantiallyinclined rearward providing relative velocity components of said fluidnormal to said edge of subsonic values relative thereto, an auxiliaryelement in each said passage extending radially thereacross oversubstantially the whole radial extent thereof and subject to saidsupersonic relative velocity therein with the leading edge of saidelement adjacent to said throat, the forward portion of said auxiliaryelement being sufiiciently blunt to precipitate a shock wave to reducesaid supersonic velocity, and a shaft secured to said hub for rotatingsaid rotor in said case at blade tip speeds relative to adjacent saidfluid greater than the velocity of sound in said fluid upstream adjacentsaid blades during operation of said compressor, said case havingcircular cross sections thereof donwstream adjacent said rotor free offluid turning stator vanes for receiving fluid across said sections fromsaid rotor with chiefly a peripheral component of velocity, said casehaving a discharge duct directed transversely to said axis for directingfluid from said case transversely to said axis, said auxiliary elementsalso defining flow passages therebetween bounded by said hub and caseand increasing in cross sectional areas rearward therealong.

4. In combination in an axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprising ahub and a plurality of peripherally spaced main blades carried thereon,said blades and said hub and said case in cooperation defining rotorflow passages for conduction of said fluid therein at supersonicvelocity relative to said rotor, each said passage having a frontportion of decreasing cross sectional area rearward therealong succeededby a portion of rearward increasing cross sectional area defining athroat of each said passage between the front and rear sides of saidrotor reducing said supersonic velocity to a lower value thereof at saidthroat, each said blade having its leading edge substantially inclinedrearward providing relative velocity components of said fluid normal tosaid edge of subsonic values relative thereto, an auxiliary element ineach said passage extending radially thereacross over substantially thewhole radial extent thereof and subject to said supersonic relativevelocity therein with the leading edge of said element downstream fromsaid throat, said auxiliary element having a blade shape of sufflcientperipheral thickness to precipitate a shock wave to reduce saidsupersonic velocity, and a shaft secured to said hub for rotating saidrotor in said case at blade tip speeds relative to adjacent said fluidgreater than the velocity of sound in said fluid upstream adjacent saidblades during operation of said compressor, said case having circularcross sections thereof downstream adjacent said rotor free of fluidturning stator vanes for receiving fluid across said section from saidrotor with chiefly a peripheral component of velocity, said case havinga discharge duct directed transversely to said axis for directing fluidfrom said case transversely to said axis, said auxiliary elements alsodefining flow passages therebetween bounded by said hub and case andincreasing in cross sectional areas rearward therealong.

5. In combination in an axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprising ahub and a plurality of peripherally spaced main blades carried thereon,said blades and said hub and said case in cooperation defining rotorflow passages for conduction of said fluid therein at supersonicvelocity relative to said rotor, each said passage having a frontportion of decreasing cross sectional area rearward therealong succeededby a portion of rearward increasing cross sectional area defining athroat of each said passage between the front and rear sides of saidrotor reducing said supersonic velocity to a lower value thereof at saidthroat, each said blade having its leading edge substantially inclinedproviding relative velocity components of said fluid normal to said edgeof subsonic values relative thereto, an auxiliary element in each saidpassage extending radially thereacross over substantially the wholeradial extent thereof and subject to said supersonic relative velocitytherein, said elements each having its leading edge positioned adjacentsaid throat and having sufficiently curved contours to precipitate shockwaves within said passage adjacent to or downstream of said throat to.convert said supersonic velocity to static pressure during operation ofsaid compressor, and

a shaft secured to said hub for rotating said rotor in said case atblade tip speeds relative to adjacent said fluid greater than thevelocity of sound in said fluid upstream adjacent said blades duringoperation of said compressor, said case having circular cross sectionsthereof downstream adjacent said rotor free of fluid turning statorvanes for receiving fluid across said sections from said rotor withchiefly a peripheral component of velocity, said case having a dischargeduct directed transversely to said axis for directing fluid from saidcase transversely to said axis, said auxiliary elements also definingflow passages therebetween bounded by said hub and case and increasingin cross sectional areas rearward therealong.

6. In combination in an axial flow compressor for an elastic fluid, acase, an axial flow rotor mounted for rotation in said case comprising ahub and a plurality of periphally spaced main blades carried thereon,said blades and said hub and said case in cooperation defining rotorflow passages for conduction of said fluid therein at supersonicvelocity relative to said rotor, each said passage having a portion ofrearward increasing cross sectional area, each said blade having itsleading edge substantially inclined providing relative velocitycomponents of said fluid normal to said edge of subsonic values relativethereto, an auxiliary element in each said passage extending radiallythereacross over substantially the whole radial extent thereof andsubject to said supersonic relative velocity therein, said elements eachhaving its leading edge positioned downstream from the leading edges ofsaid blades and having substantial peripheral thickness at the nose ofsaid element to precipitate shock waves said passages adjacent to ordownstream of said throat to convert said supersonic velocity to staticpressure during operation of said compressor, and a shaft secured tosaid hub for rotating said rotor in said case at blade tip speedsrelative to adjacent said fluid greater than the velocity of sound insaid fluid upstream adjacent said blades during operation of saidcompressor, said case having circular cross sections thereof downstreamadjacent said rotor free of fluid turning stator vanes for receivingfluid across said sections from said rotor with chiefly a peripheralcompo nent of velocity, said case having a discharge duct directedtransversely to said axis for directing fluid from said casetransversely to said axis, the leading edge of each said auxiliaryelement being positioned nearer the center of each said rotor passagethan to said blades defining said passage.

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